diff mbox series

[RFC,V2,02/10] C-SKY: TLS support

Message ID 4b02034496617cddcca1a9443ac1a990d5b77710.1523169833.git.han_mao@c-sky.com
State New
Headers show
Series port C-SKY to glibc | expand

Commit Message

毛晗 April 8, 2018, 7:02 a.m. UTC 
This patch implements TLS support for C-SKY. We support all four
standard TLS addressing modes (LE, IE, LD, and GD) when running on
Linux via NPTL.

        * sysdeps/csky/dl-tls.h: New file
        * sysdeps/csky/libc-tls.c: New file
        * sysdeps/csky/nptl/tcb-offsets.sym: New file
        * sysdeps/csky/nptl/tls.h: New file
        * sysdeps/csky/stackinfo.h: New file
---
 sysdeps/csky/dl-tls.h             |  26 ++++++
 sysdeps/csky/libc-tls.c           |  32 +++++++
 sysdeps/csky/nptl/tcb-offsets.sym |  11 +++
 sysdeps/csky/nptl/tls.h           | 179 ++++++++++++++++++++++++++++++++++++++
 sysdeps/csky/stackinfo.h          |  32 +++++++
 5 files changed, 280 insertions(+)
 create mode 100644 sysdeps/csky/dl-tls.h
 create mode 100644 sysdeps/csky/libc-tls.c
 create mode 100644 sysdeps/csky/nptl/tcb-offsets.sym
 create mode 100644 sysdeps/csky/nptl/tls.h
 create mode 100644 sysdeps/csky/stackinfo.h

Comments

Joseph Myers April 17, 2018, 8:50 p.m. UTC | #1 
On Sun, 8 Apr 2018, Mao Han wrote:

> +/* Default to an executable stack.  PF_X can be overridden if PT_GNU_STACK is
> + * present, but it is presumed absent.  */
> +#define DEFAULT_STACK_PERMS (PF_R|PF_W|PF_X)

This is not an appropriate default for a new port.  (Of course you need to 
fix your kernel port accordingly so it doesn't default to an executable 
stack either.)

Also, globally in the port, no leading '*' on second and subsequent lines 
of comments.
毛晗 April 26, 2018, 7:33 a.m. UTC | #2 
Hi,
On Tue, Apr 17, 2018 at 08:50:03PM +0000, Joseph Myers wrote:
> On Sun, 8 Apr 2018, Mao Han wrote:
> 
> > +/* Default to an executable stack.  PF_X can be overridden if PT_GNU_STACK is
> > + * present, but it is presumed absent.  */
> > +#define DEFAULT_STACK_PERMS (PF_R|PF_W|PF_X)
> 
> This is not an appropriate default for a new port.  (Of course you need to 
> fix your kernel port accordingly so it doesn't default to an executable 
> stack either.)
> 
> Also, globally in the port, no leading '*' on second and subsequent lines 
> of comments.
>
So just define to #define DEFAULT_STACK_PERMS (PF_R|PF_W). We have no 
memory executable on our hardware. So seems not need to change on the
kernel side?

Best Regards,
Mao Han
Joseph Myers April 26, 2018, 4 p.m. UTC | #3 
On Thu, 26 Apr 2018, Mao Han wrote:

> Hi,
> On Tue, Apr 17, 2018 at 08:50:03PM +0000, Joseph Myers wrote:
> > On Sun, 8 Apr 2018, Mao Han wrote:
> > 
> > > +/* Default to an executable stack.  PF_X can be overridden if PT_GNU_STACK is
> > > + * present, but it is presumed absent.  */
> > > +#define DEFAULT_STACK_PERMS (PF_R|PF_W|PF_X)
> > 
> > This is not an appropriate default for a new port.  (Of course you need to 
> > fix your kernel port accordingly so it doesn't default to an executable 
> > stack either.)
> > 
> > Also, globally in the port, no leading '*' on second and subsequent lines 
> > of comments.
> >
> So just define to #define DEFAULT_STACK_PERMS (PF_R|PF_W). We have no 
> memory executable on our hardware. So seems not need to change on the
> kernel side?

I believe the relevant kernel definitions to check, to make sure that the 
kernel does not give execute permissions to stack pages by default, are 
elf_read_implies_exec and VM_STACK_DEFAULT_FLAGS / VM_DATA_DEFAULT_FLAGS.
Guo Ren April 27, 2018, 1:55 a.m. UTC | #4 
Thx Joseph,

On Thu, Apr 26, 2018 at 04:00:17PM +0000, Joseph Myers wrote:
> I believe the relevant kernel definitions to check, to make sure that the 
> kernel does not give execute permissions to stack pages by default, are 
> elf_read_implies_exec and VM_STACK_DEFAULT_FLAGS / VM_DATA_DEFAULT_FLAGS.
For c-sky kernel:
 - elf_read_implies_exec is return 0 which defined in include/linux/elf.h
 - VM_STACK_DEFAUT_FLAGS is the same with VM_DATA_DEFAULT_FAGS defined
   in include/linux/mm.h.
 - VM_DATA_DEFAULT_FLAGS is defined in csky/include/asm/page.h:
     #define VM_DATA_DEFAULT_FLAGS \
               (VM_READ    | VM_WRITE    | VM_EXEC | \
                VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC)

And our hardware mmu tlb-entry do not have EXEC bit to protect the
page-non-exec.
So we put VM_EXEC as default in VM_DATA_DEFAULT_FLAGS.

Use generic elf_read_implies_exec seems wrong and we should "return 1",
isn't it?

Best Regards
 Guo Ren
Joseph Myers April 27, 2018, 12:10 p.m. UTC | #5 
On Fri, 27 Apr 2018, Guo Ren wrote:

> And our hardware mmu tlb-entry do not have EXEC bit to protect the
> page-non-exec.

I'm not sure what's best in the kernel for hardware not supporting 
readable but non-executable pages.

However, whatever the solution, I'd say the following principle applies to 
userspace code: binaries that require execution of code on stack pages 
should be distinguished from those that do not, and the latter should be 
the default, so that if a future hardware version does support readable 
but non-executable pages, existing binaries can automatically get 
non-executable stacks when run on the new hardware.
Guo Ren April 29, 2018, 8:49 a.m. UTC | #6 
On Fri, Apr 27, 2018 at 12:10:19PM +0000, Joseph Myers wrote:
> However, whatever the solution, I'd say the following principle applies to 
> userspace code: binaries that require execution of code on stack pages 
> should be distinguished from those that do not, and the latter should be 
> the default, so that if a future hardware version does support readable 
> but non-executable pages, existing binaries can automatically get 
> non-executable stacks when run on the new hardware.
Ok, got it.

Thx
 Guo Ren
diff mbox series

Patch

diff --git a/sysdeps/csky/dl-tls.h b/sysdeps/csky/dl-tls.h
new file mode 100644
index 0000000..d44fc18
--- /dev/null
+++ b/sysdeps/csky/dl-tls.h
@@ -0,0 +1,26 @@ 
+/* Thread-local storage handling in the ELF dynamic linker.  C-SKY version.
+   Copyright (C) 2018 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library.  If not, see
+   <http://www.gnu.org/licenses/>.  */
+
+/* Type used for the representation of TLS information in the GOT.  */
+typedef struct
+{
+  unsigned long int ti_module;
+  unsigned long int ti_offset;
+} tls_index;
+
+extern void *__tls_get_addr (tls_index *ti);
diff --git a/sysdeps/csky/libc-tls.c b/sysdeps/csky/libc-tls.c
new file mode 100644
index 0000000..30baf62
--- /dev/null
+++ b/sysdeps/csky/libc-tls.c
@@ -0,0 +1,32 @@ 
+/* Thread-local storage handling in the ELF dynamic linker.  C-SKY version.
+   Copyright (C) 2018 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library.  If not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <csu/libc-tls.c>
+#include <dl-tls.h>
+
+/* On C-SKY, linker optimizations are not required, so __tls_get_addr
+   can be called even in statically linked binaries.  In this case module
+   must be always 1 and PT_TLS segment exist in the binary, otherwise it
+   would not link.  */
+
+void *
+__tls_get_addr (tls_index *ti)
+{
+  dtv_t *dtv = THREAD_DTV ();
+  return (char *) dtv[1].pointer.val + ti->ti_offset;
+}
diff --git a/sysdeps/csky/nptl/tcb-offsets.sym b/sysdeps/csky/nptl/tcb-offsets.sym
new file mode 100644
index 0000000..8da750b
--- /dev/null
+++ b/sysdeps/csky/nptl/tcb-offsets.sym
@@ -0,0 +1,11 @@ 
+#include <sysdep.h>
+#include <tls.h>
+
+--
+
+-- Derive offsets relative to the thread register.
+#define thread_offsetof(mem)	(long)(offsetof(struct pthread, mem) - sizeof(struct pthread))
+
+MULTIPLE_THREADS_OFFSET		thread_offsetof (header.multiple_threads)
+TID_OFFSET			thread_offsetof (tid)
+POINTER_GUARD                   offsetof (tcbhead_t, pointer_guard)
diff --git a/sysdeps/csky/nptl/tls.h b/sysdeps/csky/nptl/tls.h
new file mode 100644
index 0000000..7b490c2
--- /dev/null
+++ b/sysdeps/csky/nptl/tls.h
@@ -0,0 +1,179 @@ 
+/* Definitions for thread-local data handling.  NPTL/csky version.
+   Copyright (C) 2018 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library.  If not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#ifndef _TLS_H
+#define _TLS_H 1
+
+#ifndef __ASSEMBLER__
+
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdint.h>
+#include <dl-dtv.h>
+
+#ifdef __CSKYABIV2__
+/* define r31 as thread pointer register. */
+#define READ_THREAD_POINTER() \
+    ({ void *__result;						\
+       __asm__ __volatile__ ("mov %0, r31"			\
+                             : "=r" (__result));		\
+       __result; })
+#else
+#define READ_THREAD_POINTER() \
+    ({ register unsigned int __result __asm__("a0");		\
+       __asm__ __volatile__ ("trap 3;"				\
+                             : "=r" (__result) : : );		\
+       __result; })
+#endif
+
+#else /* __ASSEMBLER__ */
+#include <tcb-offsets.h>
+#ifdef __CSKYABIV2__
+/* define r31 as thread pointer register. */
+#define READ_THREAD_POINTER() \
+       mov r0, r31;
+#else
+#define READ_THREAD_POINTER() \
+       trap 3;
+#endif
+#endif /* __ASSEMBLER__ */
+
+#ifndef __ASSEMBLER__
+
+/* Get system call information.  */
+#include <sysdep.h>
+
+/* The TP points to the start of the thread blocks.  */
+#define TLS_DTV_AT_TP	1
+#define TLS_TCB_AT_TP	0
+
+/* Get the thread descriptor definition.  */
+#include <nptl/descr.h>
+
+typedef struct
+{
+  dtv_t *dtv;
+  void *private;
+  uintptr_t pointer_guard;
+} tcbhead_t;
+
+/* This is the size of the initial TCB.  */
+#define TLS_INIT_TCB_SIZE	sizeof (tcbhead_t)
+
+/* Alignment requirements for the initial TCB.  */
+#define TLS_INIT_TCB_ALIGN	8
+
+/* This is the size of the TCB.  */
+#define TLS_TCB_SIZE		sizeof (tcbhead_t)
+
+/* Alignment requirements for the TCB.  */
+#define TLS_TCB_ALIGN		8
+
+/* This is the size we need before TCB.  */
+#define TLS_PRE_TCB_SIZE	sizeof (struct pthread)
+
+/* The thread pointer tp points to the end of the TCB.
+   The pthread_descr structure is immediately in front of the TCB.  */
+#define TLS_TCB_OFFSET		0
+
+/* Install the dtv pointer.  The pointer passed is to the element with
+   index -1 which contain the length.  */
+#define INSTALL_DTV(tcbp, dtvp) \
+  (((tcbhead_t *) (tcbp))->dtv = (dtvp) + 1)
+
+/* Install new dtv for current thread.  */
+#define INSTALL_NEW_DTV(dtv) \
+  (THREAD_DTV() = (dtv))
+
+/* Return dtv of given thread descriptor.  */
+#define GET_DTV(tcbp) \
+  (((tcbhead_t *) (tcbp))->dtv)
+
+#define TLS_DEFINE_INIT_TP(tp, pd) void *tp = (pd) + 1
+
+/* Code to initially initialize the thread pointer.  This might need
+   special attention since 'errno' is not yet available and if the
+   operation can cause a failure 'errno' must not be touched.  */
+#define TLS_INIT_TP(tcbp) \
+  ({ INTERNAL_SYSCALL_DECL (err);					\
+     long result_var;							\
+     result_var = INTERNAL_SYSCALL (set_thread_area, err, 1,		\
+                    (char *) (tcbp) + TLS_TCB_OFFSET);			\
+     INTERNAL_SYSCALL_ERROR_P (result_var, err)				\
+       ? "unknown error" : NULL; })
+
+/* Return the address of the dtv for the current thread.  */
+#define THREAD_DTV() \
+  (((tcbhead_t *) (READ_THREAD_POINTER () - TLS_TCB_OFFSET))->dtv)
+
+/* Return the thread descriptor for the current thread.  */
+#undef THREAD_SELF
+#define THREAD_SELF \
+ ((struct pthread *) (READ_THREAD_POINTER ()				\
+              - TLS_TCB_OFFSET - TLS_PRE_TCB_SIZE))
+
+/* Magic for libthread_db to know how to do THREAD_SELF.  */
+#define DB_THREAD_SELF \
+  CONST_THREAD_AREA (32, sizeof (struct pthread))
+
+/* Access to data in the thread descriptor is easy.  */
+#define THREAD_GETMEM(descr, member) \
+  descr->member
+#define THREAD_GETMEM_NC(descr, member, idx) \
+  descr->member[idx]
+#define THREAD_SETMEM(descr, member, value) \
+  descr->member = (value)
+#define THREAD_SETMEM_NC(descr, member, idx, value) \
+  descr->member[idx] = (value)
+
+/* Set the pointer guard field in the TCB head.  */
+# define THREAD_GET_POINTER_GUARD() \
+  THREAD_GETMEM (((tcbhead_t *) READ_THREAD_POINTER ()), pointer_guard)
+#define THREAD_SET_POINTER_GUARD(value) \
+  THREAD_SETMEM (((tcbhead_t *) READ_THREAD_POINTER ()), pointer_guard, value)
+#define THREAD_COPY_POINTER_GUARD(descr) \
+  ((tcbhead_t *) ((char *) (descr) + TLS_PRE_TCB_SIZE))->pointer_guard	      \
+   = THREAD_GET_POINTER_GUARD()
+
+/* Get and set the global scope generation counter in struct pthread.  */
+#define THREAD_GSCOPE_IN_TCB      1
+#define THREAD_GSCOPE_FLAG_UNUSED 0
+#define THREAD_GSCOPE_FLAG_USED   1
+#define THREAD_GSCOPE_FLAG_WAIT   2
+#define THREAD_GSCOPE_RESET_FLAG() \
+  do									      \
+    { int __res								      \
+	= atomic_exchange_rel (&THREAD_SELF->header.gscope_flag,	      \
+			       THREAD_GSCOPE_FLAG_UNUSED);		      \
+      if (__res == THREAD_GSCOPE_FLAG_WAIT)				      \
+	lll_futex_wake (&THREAD_SELF->header.gscope_flag, 1, LLL_PRIVATE);    \
+    }									      \
+  while (0)
+#define THREAD_GSCOPE_SET_FLAG() \
+  do									      \
+    {									      \
+      THREAD_SELF->header.gscope_flag = THREAD_GSCOPE_FLAG_USED;	      \
+      atomic_write_barrier ();						      \
+    }									      \
+  while (0)
+#define THREAD_GSCOPE_WAIT() \
+  GL(dl_wait_lookup_done) ()
+
+#endif /* __ASSEMBLER__ */
+
+#endif	/* tls.h */
diff --git a/sysdeps/csky/stackinfo.h b/sysdeps/csky/stackinfo.h
new file mode 100644
index 0000000..7b5eb65
--- /dev/null
+++ b/sysdeps/csky/stackinfo.h
@@ -0,0 +1,32 @@ 
+/* This file contains a bit of information about the stack allocation
+   of the processor.  C-SKY version.
+   Copyright (C) 2018 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library.  If not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#ifndef _STACKINFO_H
+#define _STACKINFO_H	1
+
+#include <elf.h>
+
+/* On C-SKY the stack grows down.  */
+#define _STACK_GROWS_DOWN	1
+
+/* Default to an executable stack.  PF_X can be overridden if PT_GNU_STACK is
+ * present, but it is presumed absent.  */
+#define DEFAULT_STACK_PERMS (PF_R|PF_W|PF_X)
+
+#endif	/* stackinfo.h */